The subject matter disclosed herein relates to gas turbine engines, and more particularly to a fuel routing system of such gas turbine engines, as well as a method of routing fuel therein.
Gas turbine engines are often connected to an electrical load, such as a generator for supplying electrical power. Significant generator speed overshoot may occur if the electrical load is instantaneously removed, thereby causing a transient condition. The transient condition may take place when either a utility breaker to an external grid or the generator breaker trips to an open state. Generator speed overshoot may cause damage to associated equipment as a result of over-frequency of the generator. Additionally, if the generator speed overshoot is above a predetermined threshold, control of the gas turbine engine will command an emergency shutdown and force an operator to conduct a time consuming and costly gas turbine engine restart cycle. Prior efforts to overcome such issues have included quickly reducing fuel flow in response to recognition of the transient condition, thereby reducing fuel flow to a minimum level needed to sustain combustion in an attempt to reduce generator speed overshoot. Unfortunately, this approach provides little to no margin to generator over-frequency limits as generators become lighter and less expensive.